THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA LOS ANGELES A'-< OPERATIVE DENTISTRY IN TWO VOLUMES. VOLUME ONE, THE PATHOLOGY OF THE HARD TISSUES OF THE TEETH GLOSSARY AND INDEX. 187 ILLUSTRATIONS. BT G. V. BLACK, M.D., D.D.S., Sc.D., LL.D. DEAN AND PROFESSOR OF OPERATIVE DBNTI8TRT, DENTAL PATHOLOGY AND BACTKRIOLOGT NORTHWESTERN UNIVERSITT DENTAL SCHOOL. FIFTH EDITION CHICAGO: MEDICO-DENTAL PUBLISHING COMPANY. LONDON: CLAUDIUS ASH. SONS & CO., LTD. 1922. Entered; according to Act of Congress, in the year 1922, by the Medico-Dental Publishing Co., in the Office of the Librarian of Congress, Washington, D. C. Entered at Stationers' Hall, London, Eng. THE HENRY 0. SHEPARD CO., PRINTERS, CHICAGO. WU 300 PREFACE. v-' The original intention in writing this book was to confine it strictly to a consideration of dental caries and its treatment, but later atrophy and erosion of the teeth were added. Atrophy of the teeth seems now to have been completely made out both as to its causation and the principal forms of the injury to the hard tissues of the teeth, and it was thought best to place this infor- mation on record in permanent form. Much of the detail as to these injuries may, however, be discovered in the future. Our information regarding erosion is far from complete and it now seems probable that much time may elapse before its investi- gation will develop satisfactory results. Its apparent increase in frequency and the great damage it is doing, calls for the clos- est study that the profession can give. Otherwise than the presentation of these two conditions, this book will be confined strictly to the consideration of dental caries and its treatment. This comprises the main features of Oper- ative Dentistry, though in fact it is only one department of our daily work at the chair. Diseases of the dental pulp, diseases of the peridental membranes, alveolar abscess, and the whole group of pathological conditions of the soft tissues, are subjects for another volume. The time has passed for including in one book all of the subjects of dentistry. While I have not been unmindful of the needs of the general practitioner in the preparation of the book, it has been planned especially for use of students in dental schools. The subjects are introduced and carried forward step by step, from the sim- pler to the more complex, with complete explanations of the nomenclature for the beginner in the work of preparing cavities and filling teeth. In the treatment of this subject, the questions of the pathology of caries applicable to the prevention of recur- rence of decay after fillings have been made, and the conditions under which operations should or should not be done, have been repeated often in order to keep these matters constantly before the mind of the student. In the arrangement of the matter, the logical order usually observed in books has been followed. That is, the pathology has been presented first and the treatment later. This is not always IV PATHOLOGY OF THE HAED TISSUES OF THE TEETH. the best order in teaching, and especially when the subjects are presented in that detail that is necessary to completeness. In order to read most understanding^ of the pathology of typhoid fever, for instance, one must have had much practical observa- tion of the disease. The more prominent facts should be obtained first and the more intimate detail added later, when personal observation has given a wider \dew. In the study of dental caries and its treatment, I have usually preferred to adopt such a plan in teaching. With that view, the second volume would be given to the student first. Following this thought, an outline of the principal points of the pathology involved is usually given with or preceding the treatment of each class of dental caries. In the first study by which the student is prepared for the begin- ning of the practical observation and treatment of caries, this answers the purpose. The more serious study of the pathology of dental caries is then undertaken later. If this plan is adopted, the first parts of the second volume would be given the student in the operative technic course in the freshman year. This would be reviewed and completed in the junior year. The first volume would then belong to the senior year. The book may be used, however, in either order. In the order as arranged, the more serious study of the pathology coming first, the reminders introduced in the second volume will be of direct advantage. With but few exceptions, the illustrations are original. Those illustrating the preparation of cavities are reproductions of pictures made by my own brush, and the photographs and photomicrographs have been made by Dr. F. B. Noyes from specimens of my personal preparation from material I have gathered myself, which remained under my personal observa- tion and study during the entire process. I am under especial obligation to Dr. Noyes for the excellent assistance he has given in the photographic work, and to my son. Dr. Arthur D. Black, for very valuable assistance and suggestions in the preparation and arrangement of the manuscript. G. V. BLACK. Chicago, III., June 22, 1908. PREFACE. PREFACE TO SECOND EDITION. The sale of this work has now exhausted the first edition of five thousand copies. This happens to come at a time when I am unusually busy in the preparation of a work on the pathology of the dental pulp and the investing tissues of the teeth, and, as I do not feel that a revision of this work is necessary at the present time, I publish a second edition with the correction of a few errors and omissions. a. V. BLACK. Chicago, August 3, 1914. PREFACE TO THIRD EDITION. It having become necessary to print a third edition of this work, I have thought it advisable to include the essential fea- tures of the studies of Mottled Teeth, a report of which, pub- lished in the Dental Cosmos for February, 1916, was the last scientific writing by my father. It was completed but a few weeks before his death. I have also substituted in Vol. II for the chap- ter on Pulp Treatment, the chapter on the same subject as pub- lished in the Special Dental Pathology, which contains more of detail. There are also a few additional illustrations. ARTHUR D. BLACK. Chicago, August 3, 1917. PREFACE TO FOURTH EDITION. The third edition being exhausted, I have made a very few minor changes for the printing of a fourth edition. No material changes seem to be desirable at this time. ARTHUR D. BLACK. Chicago, August 3, 1920. Vi PATHOLOGY OF THE HARD TISSUES OF THE TEETH. PREFACE TO FIFTH EDITION. The only change of consequence that has been made in the way of revision for this edition has been the amplification of the chapter on Inlays in Volmne II. The effort has been made to present in concise form the most important developments in the construction of gold inlays, without entering too much into details of the various technical methods employed. It is realized that more time must elapse before our knowledge of inlay construc- tion can be properly crystallized for publication in a book. The valued assistance of Dr. Eobert E. Blackwell in the preparation of the new copy is hereby gratefully acknowledged. ARTHUR D. BLACK. Chicago, August 3, 1922. CONTENTS OF VOLUME I. PATHOLOGY OF THE HARD TISSUES OF THE TEETH. PAGE Introduction xin Dystrophies of the Teeth 1 Nomenclature 2 Histological Characteristics the Basis for Classification 3 Atrophy of the Teeth 5 Etiology 10 Histological Characteristics 13 The Deformity in the First Permanent Molars 21 Treatment 24 The Enamel Whorl 27 Wrinkled Teeth 28 White Spots in the Enamel 30 White Enamel 31 Mottled Teeth 34 Brownin 35 Histological Characteristics 35 New Problem in Dental Pathology 37 Sporadic Cases 38 Diagnosis 38 Tables of Results of Examinations of Mottled Teeth Opposite page 39 Susceptibility to Caries 40 Etiology 40 Erosion of the Teeth 42 Diagnosis of Erosion 43 Frequence of Erosion 44 Forms of Erosion 45 Etiology of Erosion 50 Treatment of Erosion 57 vii Vlll PATHOLOGY OF THE HAKD TISSUES OF THE TEETH. PAGE Caries op the Teeth ,. .: 60 Historical , , 60 General Statement ,. ... .i 65 Caries of Dentin 68 Caries of Enamel. 74 Penetration of Enamel in Pits ,. . . .i 76 Penetration of Enamel in Proximal Surfaces of Incisors 77 Superficial Spreading of Caries in Proximal Surfaces of Bicus- pids and Molars 81 A Closer Examination of the Injury to the Enamel 83 The Relation of Occlusion to the Localization of Caries 85 Penetration of Enamel in Buccal and Labial Surfaces 90 Caries as a Whole. Its Clinical Features 91 Occlusal Surface Decays in Molars 92 Proximal Surface Decays in Molars 93 Occlusal and Proximal Surface Decays in Bicuspids 97 Misplacement of Beginning Proximal Decays 100 Secondary Extensions Gingivally of Proximal Decays 101 Injuries by Interproximal Wear 104 Proximal Surface Decays in Incisors and Cuspids 107 Gingival Third Decays in Labial and Buccal Surfaces 109 Spreading of Decay Around the Teeth 113 Systemic Conditions 115 Physical Characters of the Teeth. 118 General Summary of Results of Physical Examinations of the Teeth 120 The Hardness and Softness of the Teeth 122 Faults in the Structure of the Enamel 124 Physiological and Pathological Differences between Bone and Dentin 126 Studies by Dr. J. Leon Williams 128 Sialo-semeiology 129 The Saliva 132 Acidity of the Saliva, Viscosity of the Saliva, Glutinous Deposits from the Saliva, Signs of Susceptibility and Immunity to Dental Caries. Microorganisms of the Mouth 138 TABLE OP CONTENTS. IX PAGE Utility of Studies of Dental Caries 142 Vital Phenomena in Caries. . . .,. .1 144 Sensation in Dentin 146 Obtunding Sensitive Dentin 148 Thermal Sensitiveness 150 Management of Patients 153 Cleanliness 154 Cleaning which Patients should do for Themselves, The Tooth Brush, Mouth Washes, Tooth Powders, The Toothpick, Ligature, Tape and Rubber Bands. The Force Used in Mastication in Relation to the Strength and Health of the Peridental Membrane. 161 The Force Used in Chewing Foods 161 Gnathodynamometer Records. The Force Required in the Mastication of Food 165 Phagodynamometer Records. Sensitiveness of the Peridental Membrane 168 Management op Light and Care of the Eyes 172 Examinations op the Mouth 178 Treatment of Dental Caries 188 Prophylactic Treatment of Caries by Artificial Cleaning 188 Treatment of Dental Caries by Filling 190 Curative Effect of Fillings 193 Selection of Filling Material 198 Management op Cavities by Classes ,. 203 Classification 203 Cavities of the First Class ., 204 Cavities of the Second, Third and Fourth Classes 208 Limitation of Extension for Prevention 214 Thermal Sensitiveness 219 Lodgments of Food in the Interproximal Space 220 Prophylactic Value of Form in Proximal Fillings 222 Cavities of the Fifth Class 225 Caries in Cases of Recession of the Gums 230 Esthetic Considerations 232 X PATHOLOGY OF THE HAED TISSUES OF THE TEETH. PAOB Management of Children's Teeth 235 Relation of Growth and Shedding of the Deciduous Teeth to their Treatment 237 Premature Eruptions of Teeth 238 Absorption of the Roots of the Deciduous Teeth 239 Accidents During Absorption of Roots of the Deciduous Teeth 241 Treatment of Caries of the Deciduous Teeth 247 Treatment of Decays of the Deciduous Incisors and Cuspids . . . 248 Treatment of Decays in the Deciduous Molars ^. 253 The Childhood Period of the Permanent Teeth 258 Growth of the Roots of the Permanent Teeth 258 Intercusping of the First Permanent Molars 262 Special Functions of the First Permanent Molars 263 Caries of Permanent Teeth During the Childhood Period 265 First Permanent Molars, Lingual Pits of Lateral Incisors, Proximal Cavities in the Incisor Teeth, Proximal Sur- face Decays of Lateral Incisors, Open Apical Ends of Root Canals, The Pulps of the Lateral Incisors. Glossary i.^. «-• 279 Index 307 LIST OF ILLUSTRATIONS. NUMBER Dystrophies op the Teeth 1-47 Atrophy. Hypoplasia 1-29 Incisors and cuspids 1, 2, 3, 4, 5, 6, 7, 8, 16, 17,' 22 Diagram showing positions of atrophy marks at various ages. . 9 Diagram showing lines of Retzius 10 Sections of incisors and cuspids showing zones of atrophy. .11, 12, 13, 14, 15, 18, 21, 23, 24, 25 Diagram showing zones of atrophy, Zsigmundy 15 Zone of injury from atrophy mid-length of root 19, 20 Cast showing atrophy of first' permanent molar 26 Sections of first permanent molars showing zones of atrophy 27, 28, 29 Enamel whorls 30, 31 Wrinkled teeth 32, 33, 34, 35 Wliite spots in the enamel 36, 37 White enamel 38, 39 Mottled teeth 40, 41, 42, 43, 44, 45, 46, 47 Erosion of the Teeth 48-62 Dish-shaped areas 48, 49, 61 Wedge-shaped areas 50, 51, 52 Flattened areas 53, 54, 55 Irregular areas , .■ 56 Figured areas 57, 58, 59, 60 Gold crown cut by erosion 61 Proximal surface erosion - 62 Caries of the Teeth 63-145 Caries of Dentin 63-74 Dializer 63, 64 Salts dialized from saliva 65 Crystals of sugar 66 Tooth split to show area of decay 67 Occlusal surfaces of molars 68, 69, 70 Split teeth 71, 72 Dentinal tubules containing microorganisms 73, 74 xi Xii PATHOLOGY OF THE HARD TISSUES OF THE TEETH. NUMBER Caries of Enamel • 75-103 Occlusal surfaces, pit decays, split teeth 75, 76, 77 Proximal surface decays in incisors : Proximal surface 78 Split teeth 79, 80, 81 Photomicrographs of sections 82, 83, 84, 85 Proximal surface decays in bicuspids and molars : Proximal surfaces 86, 87, 88, 89, 90, 91 Cross cuts 92, 93, 94, 95 Photomicrographs of sections showing the injury to the enamel by caries 96, 97, 98 Relation of occlusion to the localization of caries: Buccal vicAv of bicuspids and molars 99 Occlusal view of bicuspids and molars 100 Normal occlusion, buccal view , 101 Occlusal views of upper and lower teeth 102, 103 Caries as a Whole, Its Clinical Features 104-145 Occlusal surface decays in molars, split teeth 104, 105, 106 Proximal surface decays in molars, split teeth. .107, 108, 109, 110, 111 Occlusal and proximal surface decays in bicuspids: Split teeth 112, 113, 114, 117, 118 Photomicrographs of sections 115, 116 Misplacement of beginning decays, central incisor .119, 120 Secondary extensions gingivally of proximal decays, photomi- crographs of sections 121, 122, 123 Injuries by interproximal wear 124, 125, 126, 127, 128 Proximal surface decays in incisors and cuspids : Proximal surfaces 129, 130 Split teeth 131, 132, 133 Gingival third decays of buccal and labial surfaces. .134, 135, 136, 137, 138, 139, 140, 141 Spreading of decay around the teeth 142, 143, 144, 145 Systemic Conditions 146-158 Physical characters of the teeth, photomicrographs of sections of enamel .146, 147, 148, 149, 150 Physiological and pathological differences between bone and dentin, photomicrographs : Cross section of bone 151 Lengthwise section of bone. ,. 152 Cross section of root of tooth showing absorption 153 LIST OF ILLUSTRATIONS. Xlll NUMBER Section of bone, showing absorption 154 Section of root of tooth, showing repair of absorption by cementum 155 Plaques on the teeth, photomicrographs of sections of teeth and plaques, Williams 156, 157, 158 Vital Phenomena in Caries 159-161 Diagram illustrating sensation without nerves in dentin 159 Split incisors, showing abrasion 160, 161 Force op Mastication 162-166 Gnathodynamometer, for measuring strength of bite 162, 163 Dynamometer, with micrometer attachment for determining stress a substance will bear without crushing, also the com- pression under stress 164, 165 Phagodynamometer, for measuring force required to chew food . 166 Treatment op Dental Caries by Filling, Photomicrograph op Salts Dialized from Saliva. 167 Caries in Cases op Recession op the Gums, Treatment by Silver Nitrate .168, 169, 170, 171 Management op Children's Teeth 172-186 Diagram showing calcification of the deciduous teeth.. 172 Diagram showing absorption of the roots of the deciduous teeth 173 Apex of root of deciduous incisor forced through gum by per- manent tooth 174, 175, 176 Treatment of caries of the deciduous teeth : Labial view of deciduous incisors 177 Lingual view of deciduous incisors 178 Proximal decays of deciduous incisors treated by filing and silver nitrate 179, 180, 181, 182 Proximal decays of deciduous molars treated by cutting and silver nitrate 183, 184, 185, 186 Childhood Period op the Permanent Teeth. Diagram showing calcification, period of eruption, and time of completion of roots of the permanent teeth 187 Pathology of the Hard Tissues of the Teeth. INTRODUCTION. THE injuries which occur to the hard tissues of the teeth dur- ing their development, and which occur to them by accident or disease after they have grown, are peculiar to the enamel and dentin. They have no apparent relation or natural kinship with similar developmental or acquired injuries or diseases of other tissues of the body, except some atrophic injuries to the hair and nails. This is made so by the histological structure of these tissues, in that they have no power of repair and recovery from injuries. The hair, nails, and the continuous growing teeth of a few animals, while having no means of repair of developmental or acquired injuries, dispose of the injured parts by the pro- vision for the wearing away of the substance, and with this the defects. Growth continues to supply new material, and in this negative way may effect a repair. The soft tissue appendages of the teeth, however, as the pulps, peridental membranes, alveolar processes, gums, etc., are developed under similar histological, physiological and patho- logical laws as other soft tissues and bones ; and possess similar powers of repair. The developmental injuries are confined to failure in develop- ment of parts of the enamel and dentin because of general sys- temic conditions which interfere with nutrition at a time when some particular part of the tooth is being formed, or is growing, and the injury is confined to that part. Other tissues have the power of repair of such injuries later. Since the enamel and dentin do not have this power of self-repair, such injuries in them are permanent. There is a similar failure of self-repair in these tissues when injured by accident or disease after they have been formed, or have grown and completed their develop- ment, such as accidental breakage of parts or injuries by erosion or by caries. As these tissues are not subject to inflammation, XVI PATHOLOGY OF THE HAED TISSUES OF THE TEETH. nor to physiological or pathological changes in the same sense in which these occur in soft tissues and the bones, and as they are amenable to treatment only by artificial repair, it seems especially fit and desirable that these be considered in a group to themselves. Those conditions that occur in the form of malformations or misbuildings, such as supernumerary teeth, odontomes, mal- formed teeth, etc., belong to a different class and require totally different treatment. The type of dystrophy, which has been commonly designated as atrophy of the teeth, is met with so frequently in the practice of operative dentistry, and the injuries of the teeth are often so severe, that it has seemed to me that the facts gathered by recent investigations should be placed in permanent form in our litera- ture. Until very recently little had been accurately known of the foiTus of these lesions, and many errors are being made in the treatment which may be avoided by a closer study of the condi- tions. While in many cases but little can be done to improve the appearance of affected incisors, a large proportion of the first molars which are now lost may be protected and remain useful in mastication, as well as to serve their full purpose in the development of the features. On the subject of erosion, much greater interest is being manifested in recent years than formerly; the interest in its pathology has been increased by recent investigations and the continuance of these should be stimulated with the hope that its causation may become more definitely known and some satis- factory cure or preventive discovered. The subject of dental caries and its treatment is and must remain the most important subject in conservative dentistry. No great improvement in its treatment can be had without improvement in the understanding of its causation, the condi- tions of the beginnings of caries of the enamel and the means to be employed in the prevention of its recurrence about the mar- gins of fillings. To this end, extensive studies have been made of this particular phase of the subject with the view of placing that which is now known in systematized, usable form, for both students in dental schools and for practitioners. This feature of operative dentistry has been deemed of so much importance to the dental profession and to our people that, in writing of technical procedures in filling teeth, it has been held continuously before the mind of the student and practitioner by frequent INTBODUCTION. XVll explanations and repetitions. This has seemed necessary because of the general disregard of the study of dental caries in its rela- tion to treatment by filling shown by most recent writers. It is intrinsically wrong to treat the subject of filling teeth simply from the mechanical standpoint ; it is wrong in that it tends to produce in the minds of students the idea that filling teeth is a purely mechanical pursuit. This is far from the proper concep- tion of the facts. In filling teeth, the closest use of our knowl- edge of the pathology of dental caries and of the local conditions of its occurrence, and of its recurrence after fillings have been made, should be put to full use in every case, in order that the greatest benefit may be derived from filling operations. To state this in the fullest detail has been a special object. To this end, studies have been made of dental caries and the various forms it assumes in its beginnings in the enamel, spread- ing of colonies of microorganisms on the surface of the enamel, carrying with them the spreading of beginnings of caries into the surface of the enamel, and the manner of penetration of the enamel. These have been carefully illustrated by photographs and photomicrographs, beginning with the simplest forms, and, by careful arrangement, proceeding to the more complex through the different phases. There have been included, so far as seemed possible by this method, illustrations of the directions of this spreading and the local conditions which favor it and which hinder or prevent it. The areas of the surfaces of the teeth rela- tively most susceptible to the beginnings of caries, as differen- tiated from the immune or relatively immune areas, have also been illustrated. On account of the extreme importance in the practical operations of filling teeth of this particular phase of the subject, it has been illustrated, with two or three exceptions only, by photographs and photomicrographs reproduced by the half-tone method without any retouching or artificial modifica- tion in any way. To these a few diagrammatic illustrations have been added. The fact has been kept prominent that immunity to dental caries, which may be complete, or which will approach complete- ness, even in persons, who, as children, were very susceptible to caries, will become established in early adult life in the larger proportion of cases in which effective protection has been given by filling operations, by continuance of active mastication of food, and reasonable care as to cleanliness. This matter, which was neglected because of previous misinterpretation of observed XVIU PATHOLOGY OP THE HAED TISSUES OF THE TEETH. facts, is, with continued observation, assuming greater impor- tance in dental practice. The systemic conditions producing the changes in the saliva on which susceptibility and immunity are based, while making progress, has not yet assumed any such exactness of definition as to be of immediate use in practice. In the technical procedures in filling teeth, the details of the adaptation of instruments to the work of cavity preparation have been brought into close systematization through notes of practical work at the chair representing actual operative experi- ence. This has been expressed in forms of nomenclature that are simple, systematic and effective in teaching, in pointing out defi- nitely the instruments for use and the manner of use of each. Every detail of cavity form is systematized and brought under a system of nomenclature comprised under a very few efficient rules, which render it simple and effective for teaching purposes and for general use by practitioners of dentistry. All of this has been systematized and improved through many years of actual work in teaching and has proven sufficiently flexible to cover all kinds and varieties of cases presented. The careful classifica- tion of cavities and of instrument forms adapted to each make it possible to teach cavity preparation in a way that it is easily learned; cavities may be more easily prepared, the time con- sumed is shortened, the operation is more definite in its results. Taken altogether, these mark an improvement in the effective- ness of operative dentistry. Improvements that seem to have been but little thought of heretofore have been made subjects of careful study and system- atization. Operative dentistry, particularly when closely pur- sued for years together, is extremely taxing upon the nervous system of the operator, and many men break themselves down purely through assuming positions at the chair that are unnec- essarily fatiguing. This arises from assuming wrong positions in the beginning and the failure to obtain that relief which is clearly and easily possible by change and the rest that change brings, without ceasing or slowing the work at the chair. System- atization of these matters and bringing them under forms of nomenclature in which they may be taught and discussed under- standingly should result in great good. Dentistry has its own nomenclature which has become dis- tinct from the nomenclature of comparative dental anatomy. The nomenclature of dental anatomy from the standpoint of dentistry and of operative dentistry belongs distinctively to INTRODUCTION. XlX dentistry, and should in no case be confounded with the nomen- clature of comparative dental anatomy, nor the one used in the place of the other, nor should any effort be made to harmonize them. When the human teeth are under consideration from the comparative anatomy standpoint, the nomenclature of compara- tive anatomy, which is suited to the description of the teeth of animals in general, should be used. In that nomenclature we do not speak of buccal and lingual surfaces of teeth but of inner and outer surfaces, the bicuspids in dental nomenclature become premolars in comparative dental anatomy. While there are points of coincidence in these nomenclatures, there are wide differences that could not be reconciled without positive injury to both. DYSTROPHIES OF THE TEETH. <■ ILLUSTRATIONS : FIGURES 1-47. j . "> THE condition resulting from imperfect, defective, or bad formation of growth constitutes a dystrophy ; dys — imper- fect, defective, bad; trophy — growth, development. Therefore, any dystrophy noted must have occurred during the growth of the tissue. A tooth that is misshapen, off color, or otherwise deformed during growth, is in the condition of dystrophy. Acquired deformities, such as erosion, abrasion of the teeth in chewing food, etc., after the teeth have formed, are excluded from dystrophies. The dystrophies of the teeth consist of imperfections in development due to some disturbance of nutrition during the time of formation or growth. In each class of cases some part of the tissue is either imperfectly developed, or some particular part has failed to develop, or has developed in an erratic man- ner. Among these dystrophies, there are certain things common to several, such as imperfection of the cementing substance between the enamel rods. In others, the enamel may be want- ing or may have an unusual arrangement, while in others defects may be present in all of hard tissues of the teeth. It is only recently that these conditions have received such histological study as to make out the scheme of each, and sep- arate them into special classes of deformity. The gross appear- ance of some of the more frequent of these deformities of the teeth has of course been well known for many years. All of these deformities thus far seen may be grouped in such a way that each one will be distinguished as a special deformity, and those that are essentially alike may be grouped together. Sections prepared for microscopic observation form the basis of this classification.* * These examinations have convinced me that the words atrophy and hypoplasia are no longer desirable. These words have been applied to a specific deformity of the teeth caused by malnutrition, and they have also been used almost continuously in describing abnormal teeth of any and aU classes. This they can not properly do, and it seems actually necessary that other words be substituted. The continued use of the word atrophy has become a bar to progress, and it wiU be noticed that I have in this writing substituted the word dystrophy as applied to all forms of imperfect development, and have used other terms as descriptive of the several dystrophies. I have, as in previous editions of this work, used the word atrophy as applied to that form of dystrophy caused by malnutrition, only because I am unable to find a satis- factory word to replace it. PATHOLOGY OP THE HARD TISSUES OF THE TEETH. NOMENCLATUEE.* Atrophy. Hypoplasia. Contemporaneous accretional dys- trophy. A deformity occurring along the lines of accretion, con- temporaneously in all teeth in process of development during a period of malnutrition. In this the enamel rods, the cementing substance between the rods, and the dentin are all involved and part of each is either imperfectly formed or wanting. The enamel whorl. A deformity occurring within the enamel, in which there is an abnormality of direction of the enamel rods, usually associated with a pit in a surface that is normally smooth. Wrinkled or corrugated teeth. A deformity characterized by abnormal ridges and grooves of the enamel surface, with scalloping of the dento-enamel junction, and much disarrange- ment of enamel rods. In each of these scallops there is a dis- turbance of the direction of the enamel rods. They are thrown into circles and whorls and not infrequently open cavities occur in the tissue. The condition is comparatively rare. White spots in the enamel. A deformity observed as a spot which is paper white in the enamel; a form of dystrophy in which the enamel rods are normally formed, but the cementing substance which should occupy the spaces between the rods is missing. These spots are not very frequent, and many of them are passed over without observation. They are of little impor- tance. White enamel. A deformity similar to the white spots, except that all of the enamel of the teeth is composed of rods without the cementing substance, and the crowns of all of the teeth are pure white. This is a very rare condition. Mottled enamel. An endemic deformity, distinguished espe- cially by the absence of the cementing substance between the enamel rods in the outer fourth, more or less, of the enamel, and presenting great variety of color. In certain regions of comparatively few square miles, many thousands of persons have this deformity. * Note. — Dr. Black wrote these paragraphs relative to the nomenclature of the dystrophies of the enamel only a few weeks before his death. He was not then satis- fied with the terms applied to the various dystrophies, and expressed his intention to revise them before publication. He was especially anxious to find a sample term to displace the terms atrophy and hypoplasia. In his last writing he used the term contemporaneous accretional deformity, but realized that this was too long. It seems best to retain the words atrophy and hypoplasia until a satisfactory substitute can be fonnd. dystrophies of the teeth. 3 Histological Chaeacteeistics the Basis for Classification. To one who has made careful histological studies of the structure of the teeth, these various deformities point to the need for further investigations. KJnowing, as we do, the plan on which the teeth are gradually formed from certain points of beginning, we recognize one form of dystrophy in which all of the hard structures of the various teeth that were in process of formation at a given time were imperfectly formed, due to an interruption of the normal activities of constructive cells. We note that the portions of the teeth formed both before and after the particular time are perfect. This suggests at once a gen- eral interruption in the nutritive processes during the period of malformation, and inquiry as to the health of the individual at the age indicated by the malformed part reveals the relation- ship between the two as cause and effect. We recognize another form of dystrophy in which there is a failure of the formation of the cementing substance between the enamel rods in irregular areas, notwithstanding the fact that all other structures of the same teeth, and the cementing sub- stance in other parts of these teeth, formed during the same period, are perfect. Or there may be a partial failure in the development of the enamel rods, as seen in the pits in teeth which are otherwise normal in their formation. Such conditions represent an interruption of the normal activities of certain elements of the formative cells, while cells of the same type close by have functionated properly. These contraindicate a general systemic disturbance and speak for a purely local inter- ference. We observe another form of dystrophy in which the cement- ing substance between the enamel rods is entirely wanting in all of the teeth of an individual, while every enamel rod is per- fectly formed. In this there apparently is a disturbance or lack of activity of an entire group of formative elements, and again we must think of the cause as being more general. We may imagine the lack of a certain necessary stimulus, as a result of which the cells which should form the cementing substance have failed to do so. Although no such relationship is known, the situation is comparable to the relationship between certain duct- less glands, as the thyroid and suprarenal glands, and other organs and cellular elements, the secretion from these glands in normal quantity being necessary for the proper functional activity of the related organs or cells. Again we see in the mottled teeth an endemic type of dys- trophy, confined to persons living in certain geographic areas. 4 PATHOLOGY OF THE HAED TISSUES OF THE TEETH. In this there is a failure of the formation of the cementing sub- stance between the enamel rods in the outer third only and in very irregular patches, the cementing substance between other rods being perfect. The fact is well established that these defects occur in the teeth of more than 80 per cent of persons who live in such geographic areas during the period of enamel formation. If such individuals reside in one of these known geographic areas during the period of formation of a number of the teeth, and elsewhere during the formative period of other teeth, only those which are formed during residence in the area will show the characteristic defects. These present the most difficult problem of all in relating the histologic defect to the cause, since the formation of perfect cementing substance and the lack of formation of this substance are contemporaneous in the individual tooth or several teeth. There is a local failure of cells to functionate, which is evidently the result of some general systemic condition. These observations indicate that there are separate forma- tive cells for the enamel rods and for the cementing substance between the rods ; that under certain conditions both processes are interfered with, while in others there is a failure in the for- mation of the cementing substance, but not of the rods, and in others a failure of rod formation. Future studies may deter- mine how these things come about. In the following pages the various dystrophies will be described. To get a proper understanding of these conditions in relation to the causes, it is necessary that one have a good knowledge of the histological structure and development of the teeth. There should be in mind for each tooth the average time of beginning formation and the period required for growth to completion. This is necessary to determine the age at which the cause of the particular defect was operating. If it was a condition of malnutrition its effect should be recorded by defects in the portions of all teeth in process of formation at the time. For example, at the age of three about two-thirds of the crown from occlusal to gingival of the first permanent molar has been formed ; at the same age only about the incisal third of the central incisor has been formed, usually a little less of the lateral incisor and only the tip of the cuspid. Therefore an illness at the age of three which resulted in a defect of any one of these teeth in the position mentioned should involve all of them. The defect in the cuspid could not be as far away from the incisal edge as in the central incisor, because the central is always in advance of the cuspid in its formation. (Figure 9.) DYSTROPHIES OF THE TEETH. 5 Likewise one should be familiar with the lines of accretion of the enamel — the lines of Retzius — as shown in Figure 10. Each of these lines represents a period of growth of the enamel — a layer, all of which was constructed during a given time. It is without the province of this writing to go into detail in these matters, and the student is referred to the several authori- tative works on dental histology. ATROPHY OF THE TEETH, r- It- Hypoplasia of the Teeth. A contemporaneous accretional deformity — a dystrophy in which all portions of the teeth in process of formation at a par- ticular time are imperfectly formed along the lines of normal accretion or growth. As in the previous editions of this work, the term atrophy is applied to this condition, also the term hypoplasia, which has been used widely in the German writings. Because of the fact that the application of both of these terms has been too general, has included all kinds of deformities, and also because of the fact that the term atrophy represents two distinct ideas in medi- cal literature, I am of the opinion that both terms should be dropped as applied to this condition. The term atrophy has been applied to a failure of development of a local part because of a failure of nutrition ; it has also been applied to the wast- ing of a part because of a local failure of the nutritive process. The term atrophy has been used to designate this condition since it was first spoken of in the English language. The contemporaneous accretional deformities of the teeth represent an atrophy of the first mentioned type; they have never been fully formed. They come through the gums in the condition of deformity in which they are afterward seen, and do not, as some seem to suppose, waste away after having taken their places in the arch. The deformity is a result of incomplete formation. In the human teeth there is no process of repair and the deformity is permanent. Similar phenomena occur in the finger nails and the hair. During an illness that interferes seriously with nutrition, the portion of the finger nail then forming will be dwarfed, which will appear later as a groove across the nail. This, like the marking of the teeth, is not remedied by any repar- ative process. But the nail is continuously growing and the groove moves on over the length of the nail and disappears. During a severe illness that interferes with nutrition, a sec- 6 PATHOLOGY OF THE HARD TISSUES OF THE TEETH. tion of hair is imperfectly formed, and when in the process of growth this section arrives at the surface of the skin and is sub- jected to bending, it breaks and the hair suddenly falls away. These are common phenomena following severe cases of typhoid fever. The hair follicles are not injured and the hair is replaced by the regular process of growth. In the continuously growing teeth of the rodents such an injury would be finally removed and remedied in the same way as the grooving seen upon the finger nails, but this can not occur in the human teeth. The deformity, though much varied in different cases, is, when closely analyzed, always similar in character. It always consists in a failure of the formation or an imperfect formation of some specific portion of the tooth and of several teeth together. The portion of the several teeth affected is always that portion of each that was in process of formation or growth at the same period in the person's existence. To understand this well one should study closely the calcification of the crowns of the teeth and the contemporaneous lines of calcification of the different teeth. This will be more fully explained in considering the histo- logical changes occurring in atrophy. In the incisors the de- formity is of tenest seen in the form of a groove, smooth or pitted, running across the labial surface from mesial to distal, and close inspection will generally show that it encircles the tooth com- pletely, though it is most prominent upon the labial surfaces where the enamel is thickest. It is seen more often on the incisal half of the length of the crown. It may be near the cutting edge of the tooth or anywhere from that point toward the gingival line. It is also found occasionally in the roots of extracted teeth. There may be a single groove or pitted line, or there may be two or even three or more of these. The teeth affected are the inci- sors, cuspids and first molars of the permanent set, and very rarely the first bicuspids. If it is very close to the cutting edge on the central incisors it may not appear on the laterals, but the occlusal surfaces of the first molars will be atrophied. This is because these parts of these teeth are in process of formation at the same time. If the groove is a little further removed from the incisal edge of the centrals, the lateral incisors will also be similarly affected. If it is a little higher still, the four incisors, upper and lower, the cuspids and the first molars will be affected, but the bicuspids will be free from injury. It is exceedingly rare that the bicuspids or the second or third molars are affected by atrophy, for the reason that the enamel and dentin of these teeth generally have not begun to form until after the age at which these effects are most liable to occur. But few cases occur in DYSTROPHIES OF THE TEETH. / which the first bicuspids are marked. The time of the occurrence of these injuries seems to be confined mostly to the first five years of a child's life, but some cases occur later. In the engravings the endeavor has been to illustrate some of the more severe types of these deformities and to explain by illustration the histological defects. Figure 1 represents what is known as the typical Hutchinson tooth, from the claims of Mr. Hutchinson, a specialist in venereal diseases in London, England, who insisted that this deformity was the result of inherited syph- ilis. In such cases, it has formerly been supposed that the middle lobe has failed of formation, resulting in this peculiar scar, but more recent investigation seems to show that the whole incisal edge has failed in most of these cases, and that the angles of the tooth have been drawn together over the injury, giving the out- line of the tooth this rounded appearance. Certainly many of these teeth are much shorter than normal. Generally an ugly deformity of the occlusal surfaces of the first molars accompanies this type. In the molars little spiculae of cusps are likely to be sticking up much too close together, while the rest of the occlusal surfaces are much too small, crumpled together and sunken into the crown, which, other than this, will be of full size and form. These teeth decay quickly in case there is a tendency to caries in the individual. Of the incisors shown in this illustration, only the centrals are affected. The calcification of the cutting edges of these is occasionally just begun at birth, and if not begun then, is usually begun within one year. The injury, therefore, occurs soon after the birth of the child from some cause which interferes with nutrition. A very curious fact in pathology is rendered promi- nent in this form of defect. It is this : when the nutrition of any single part of the enamel organ is so impaired that its func- tion is stopped or very seriously disturbed, that particular part does not recover, and no additional enamel is formed by that part. This will appear more prominently in the histological specimens. It is for this reason that these teeth have the peculiar rounded appearance of the cutting edge. The enamel organ of that part is arrested in its work at the very beginning of the calcification, and therefore the immediate incisal edge fails entirely. The rest of the organ goes on with its work after the recovery and the tooth is drawn in over the scar. In the incisors this form of defect is apt to be attacked by decay in this incisal pit very soon after the teeth have taken their places in the arch. They should be filled at once if decay is discovered. This par- ticular form of atrophy is seen less frequently than others. The occlusal surfaces of the first molars are occasionally 8 PATHOLOGY OF THE HABD TISSUES OF THE TEETH. badly deformed when the incisors have escaped. Usually these have just begun their calcification at birth, and occasionally the calcification of the central incisors does not begin for one year after birth. In such cases a severe illness may injure the molars and not injure the incisors. Much the more common forms are those illustrated in Fig- ures 2 and 3, the illustrations showing rather bad cases. In Figure 2 the deformity is confined to the cutting edges, appar- ently, of the central and lateral incisors above and below, and the four first molars. In the case here illustrated the whole of the incisal edge of each of the incisors above and below is dwarfed and shortened. This dwarfed portion ends abruptly toward the gingival. This is common in these cases. In many there is more or less rounding down of the well-formed part of the crown to the deformed part, but often it is so abrupt as to form a square shoulder along which there is apt to be a series of sharp, deep pits. In the case from which Figure 2 is taken there are no pits whatever, and the deformity consists purely in the dwarfing of the incisal edges. But the entire occlusal surfaces of the molars were in very bad condition because of dwarfing that presented many abrupt fissures in which decay began almost immediately after they had come through the gums. In such cases as this the appearance of the incisor teeth may be much improved by grind- ing away the dwarfed portion and shortening the cuspids a little to correspond with them. The teeth may appear a little short, but that is sometimes much less noticeable than the blemish. In other cases, occurring in the same locality and affecting the same teeth, there may be but little dwarfing of the incisal edges of the incisors. The effect may be but a slight groove that may be smooth or more or less pitted, or in cases of a still milder type the distinct groove may be lacking and a row of fine pits in the enamel will be the only deformity. Generally, the effect is more marked in the occlusal surfaces of the first molars than in the incisors. In the case illustrated in Figure 3 the injury has occurred later, when the child was between three and four years old. The incisal portion of the incisors had been formed, and, therefore, there is no dwarfing of this portion of these teeth. But there is a very marked groove encircling the crowns of the incisors and cuspids, marked with pits, with smoothly rounded bottoms. Both the groove and the pits in the groove are abrupt toward the gingi- val and thin away toward the incisal. This is a constant charac- teristic of these deformities, which will be readily understood by a study of the histological sections and the calcification lines of Retzius. The circular form of this deformity, as it passes DYSTROPHIES OF THE TEETH. 9 from tooth to tooth across the front of the mouth, is well marked in Figure 3 ; indeed, it presents rather more of the circular form than usual, indicating especially that the cuspids were a little later than usual in their calcification, and for that reason the mark is nearer the incisal edge in proportion to the position on the incisors than it would otherwise have been. It is not frequent that we see so severe a mark as here shown so high upon the labial surfaces of the incisors. It seems to be a general rule that the higher upon the teeth the less marked is the deformity. Pretty generally, in this position on the cen- trals, the mark is a shallow groove, more or less pitted, or a row of pits without a distinct groove. In all of these cases the lower teeth bear marks similar to those in the upper. In Figure 4 a case is illustrated that is somewhat out of the usual form in several particulars. When the impression for the cast from which the illustration was made was taken, the cuspids had not come through the gums, but one of the first bicuspids had erupted, and, to my surprise, showed a deep mark encircling the point of the buccal cusp. -Also the history of the case shows that the lateral incisors did not erupt for two years after the centrals had taken their places. In the centrals the incisal edges are fully formed, but there is a deep groove with rounded pits encircling the crowns at nearly mid-length, while nearly the whole incisal half of the laterals is badly deformed. This indicates that the beginning of the calcification of these teeth was late, as compared with that of the centrals. This particular form of deformity of the lateral incisors is not very frequent, but yet a considerable number have been seen, quite enough to indicate a tendency to this particular deformity. In the common vernacular this has been called the inverted finger nail deformity. If we imagine the finger nail taken up and turned with the convex side down and set back in the end of the finger, we would have something very like this deformity. The whole appearance of this case at the time of my observation of it, indicated unusual irregularity of the time of calcification and eruption of the different teeth. The first molars, both above and below, had already been destroyed by decay, beginning in the deformity of the occlusal surfaces. Figures 5 and 6 show a lower incisor with a double deform- ity. Figure 5 is a view of the labial surface, and Figure 6 of the mesial surface. The dotted lines show the normal tooth form. The two, taken together, show the extent of the dwarfing of the crown of the tooth. In this case the surface of the enamel was smooth and without pits. Figure 7 shows an upper central very badly deformed. This is also a double deformity and was further injured by decay 10 PATHOLOGY OF THE HAKD TISSUES OF THE TEETH. starting in pits in the abrupt portion of the groove nearest the incisal. The sharp, deep pits shown along the line of the second groove have not been caused by decay, but were there when the tooth came through the gums. These teeth are from different persons, and in both cases were extracted in order to remedy the defect with artificial teeth. This seems to have been done imder the mistaken notion that the roots of the teeth would not be good for artificial crowns. Extended observation shows that the roots of such teeth are as apt to be well developed and as good for crowning as those of any other teeth. When the crowns are so badly deformed that it is out of the question to employ filling operations and preserve the pulps, artificial crowns should be resorted to, rather than to remove the teeth. In case the crowning involves the removal of the pulp, this should be delayed as long as possible in order that the roots may be fully formed and the apical foramen reduced to a small size. One should wait until the patient is sixteen to eighteen years old, and twenty would be still better. In many cases of considerable actual deformity of the teeth the color remains very perfect, and in this case, if the incisal edges of the incisors are fairly complete, the deformity is not prominently noticeable, as is shown in Fig- ure 8, from a photograph taken directly from the mouth. Etiology. This deformity of the teeth is always caused by illness that has interfered with nutrition at the time the particular parts of the teeth affected were in process of calcification. My attention was strongly called to this through a controversy between Mr. Hutchinson of London, and Dr. Magitot, of Paris, who took opposite views some thirty or forty years ago. From Mr. Hutch- inson's observations he was led to believe at first that all of these cases were caused by inherited syphilis, while Dr. Magitot had come to the conclusion that they were due to eclampsia. This controversy led to a closer study of this whole subject, and finally Mr. Hutchinson yielded the point so far as to say that inherited syphilis was a frequent cause, and for many years held that the type shown in Figure 1 was always caused by inherited syphilis. That form, therefore, has been called the Hutchinson tooth. As showing how errors are liable to be per- petuated, most of the books on general medicine, surgery and venereal diseases, which mention these deformities at all, ascribe them to inherited syphilis, following the first writings of Mr. Hutchinson without further investigation. They are continually accusing innocent persons of crime. The author has followed this subject pretty carefully ever ora Fig. 1. Sj'^rr^g^J^^eS^J^^^U Fig. 2. ilAftfti'^" Fig. 3. Fig. 4. Flc. 1 Atrophy of the cutting edKe of the central incisors, forminB a central notch or scar. This is usually called " Hutchinson's tooth." In connection with this form of atrophy, the occlusal surfaces of the first molars are also badly marked. Fig 2. Atrophy of the cutting edge of the central and lateral incisors. When this occurs, some portions of the occlusal surfaces of the first molars will also be injured. Fig 3 Atrophy marks on the incisors and cuspids. In this case there is a pitted groove around the crown of each tooth atrophied. The first molars have a similar groove on their a.xial surfaces. Fig. 4. Atrophy marks on the incisors, showing the inverted fingernail scar on the lateral incisors. Fig. 5. Fig. 6. Figs. 5, 6 and 7. Single teeth, the crowns of which have been badly dwarfed by atrophy. Each of these show two zones of injury. The dotted lines are intended to show the normal out- lines of the crowns. Figures 5 and 6 .are different views of the same tooth. Fig. 8. Fig. 8. Atrophy of incisors and cuspids showing no discoloration. Photographed direct from mouth of girl eighteen years of age. Frn. 9. over wh1ch'lin?s"arrdrafvn^'epretert1ne\^e?/.^^^ ''1^ °' '^' u^'i' """'^^'^ -"^-^at enlarged, the ages named in years byXTumerlls aS ^^'"^ ^"'"^^^ '"^'"'^^ ""' «'='="■ « two years of age, etc. The rule is thLt 1n%ft * „hf^^ these 0 represents birth. 1 one year. 2 and second molars are not marked ^t^oph.es occurring before the sixth year the bicusp ds DYSTROPHIES OF THE TEETH. 11 since Mr. Hutchinson wrote, adding observation after observa- tion, and has arrived at the conclusion that there is no special form of disease that is especially blamable for this affliction, but that any form of disease that seriously interferes with nutrition is liable to bring about this result, i e., that it is not the partic- ular form of disease, but that it is the condition of malnutrition that is the cause, no matter what the disease which has induced that condition. I have seen cases of typical Hutchinson teeth which were certainly in no way connected with a syphilitic taint of any kind. Some of these observations may be of interest. Mr. and Mrs. B., known by the author intimately from childhood, had a child which seemed healthy at birth, but soon afterward became anemic and did very badly for two years. Growth was a failure during that time, and it was with great difficulty that the child was kept alive. In its third year, however, the child recovered and became strong and healthy and developed well. When the permanent teeth came through the gums, almost the incisal third of the cen- trals and laterals was badly dwarfed, the points of the cuspids had failed and the occlusal surfaces of all of the first molars were badly deformed. I attended a child two and a half years old through a severe case of typhoid fever. When the permanent teeth came through they were marked with a deep groove, irregularly pitted, similar to Figure 3, but not so high up on the crowns. An English woman brought her child to me on account of a very ugly marking of the incisors which had just come through the gums. In reply to my inquiries she could not remember that the child had had an illness of any kind. The boy had always been healthy and had escaped all of the infantile diseases. Being convinced that something had occurred that would have been noted, I asked her if the child had had any kind of an injury. This quickly brought out the statement that the child had had a severe burn, a scald, on the side and back, that had healed slowly after much suppuration. Indeed, the child had been very ill with septicemia for a month or six weeks. The time corresponded with the marks upon the teeth. Cases like these, but every one different in detail, could be multiplied almost indefinitely. Scarlet fever, measles and whooping-cough come in for a large share in producing these marks. My observations for some time led me to believe that scarlet fever and measles are most often to blame for the rows of fine pits, but of late I have found so many of these following other forms of disease that I am led to doubt the distinguishing 12 PATHOLOGY OF THE HARD TISSUES OF THE TEETH. features of these marks. Certainly, hereditary syphilis comes in for its full share of these cases. On the other hand we can not say, at least I can not, that marked teeth will result from this or that illness. If the hair falls out or the finger nails show a groove after an illness we are apt to find the teeth marked also. Very many of the cases that I have noted and watched for the coming of the permanent teeth have presented teeth without a blemish. Indeed, among all of the cases that I have noted and watched, the marked teeth have been the exception rather than the rule. Still, it remains true that when I have been able to obtain a satisfactory history, the marked teeth have coincided in time with some form of disease that might well have interfered seriously with the nutritive proc- esses. The history is not always easy to get, even among intel- ligent people. I once remarked to a lady in my chair that she had been very sick with scarlet fever when she was about two years old. She was very sure she had not, for she had never been told of such an occurrence. When I explained that accurate knowledge of the facts was of considerable scientific value she said she would question her mother regarding it. The next day I received a note saying her mother's story agreed with my sup- position, both as to the particular disease and the date of the illness. I have seen many of these cases, however, in which I could find no history of the illness causing them. To assist in searching for the cause that has led to this deformity in cases coming before us, I introduce a diagrammatic chart, or index, indicating by lines across the incisors, cuspids and first molars, the positions the grooves across the teeth assume because of disease occurring at different ages of the child. Figure 9. These lines have been varied a little from the true contemporaneous calcification lines to suit better the appar- ent positions upon teeth that are shortened by severe atrophy. This chart will point out the age at which any injury occurred as well, perhaps, as it can be done in a chart of this character, which, of course, is founded upon averages. Pretty wide varia- tions will occur in the time of the calcification of the teeth of individuals, and also between the several teeth of the same indi- vidual. There is certainly as much variation as eighteen months in the time of the beginning of the calcification of the central incisors, and a greater range possibly with all of the other teeth, except the first molars. These latter are perhaps the most con- stant. But these certainly vary from the twenty-fifth week of uterine life to something near six months after birth. The chart is intended to give only a general average as to the time of the illness that has caused these injuries. dystrophies of the teeth. ' -^ 13 Histological Characteristics. In presenting the histological characteristics in this form of dystrophy, it may be stated that all of the cases thus far examined by myself, no matter how different their outward appearance, present one plan of departure from the normal arrangement of tissues. The differences are due only to posi- tion, the number of zones of injury and in the details of severity. This plan is inseparably linked with the plan of development of the dental tissues. Except in the pits that often accompany it, the zones of injury always follow the lines of Eetzius very rigidly. In the dia- gram, Figure 10, the lines of Retzius are made especially prom- inent to recall distinctly their direction on different parts of the enamel cap of the crown of the tooth. In microscopic observa- tion these are usually clearly seen in some parts of the enamel cap, particularly in central labio-lingual sections. They vary, however, indefinitely in prominence in different sections, and in different parts of the same section. Generally, they do not show clearly in all parts of a section, and those who have not studied them carefully should refresh their memory as to the course of these lines in different positions on the crown of the tooth. These lines are the index to the growth of the enamel cap. They are the real lines of accretion and show distinctly the order in which the enamel cap is built up, layer after layer, in its growth. This growth begins at the dento-enamel junction, in positions which represent the cutting edge (or points of the cusps in molars and bicuspids) and grows from within outward, while the dentin begins its growth at the same point and progresses from without inward. The growth of dentin is always a little in advance of the enamel as it grows from the incisal edge of the front teeth (or the points of the cusps of other teeth) toward the gingival line. This contemporaneous accretional deformity, in all cases, consists of an arrest, or partial arrest, of growth of both enamel and dentin in the particular zone being developed at the particu- lar time. In the milder cases growth is imperfect, leaving certain definite markings outlining the particular parts of the tissue then being formed. In all the severe cases the growth of both enamel and dentin is arrested. There seems to be no recovery of the part of the enamel organ that was at the time in active function. No more enamel whatever is formed over the area affected after recovery from the condition of malnutrition, except as the new formation is telescoped over the area of the old. The dentin pulp, however, rebegins its growth function 14 PATHOLOGY OF THE HARD TISSUES OF THE TEETH. apparently immediately the condition of malnutrition has passed. But the parts of the tooth which should have been formed during that period are not formed at all. A certain part of the tissue which should have constituted the perfect tooth has been left out, and the distortion of form which we so often see results from patching the second growth onto the first and the total failure of particular portions of the enamel. This total failure of the enamel is not in the direction of the thickness, but is always on the lines of Retzius. Therefore, as we shall see later, there is not a failure of the total thickness of the enamel at any point, except in a f^w cases in which the injury occurs at a time when calcification was just about to begin, as sometimes occurs in the so-called Hutchinson tooth, and may, rarely, occur in others. For instance, in the diagram, Figure 10, there are four layers of enamel represented over the incisal edge. If total arrest of growth should occur at the time the first two layers are completed, the third and fourth layers will never be formed. The enamel will remain over the incisal edge with only these two layers. Then perhaps the fifth and sixth layers shown, more or less, will also fail, and the seventh and eighth layers will overlap the first and second somewhere near half their length, because the formed part of the incisal edge sinks into the dentin pulp. The dentin pulp has also stopped its growth at the same time and the part that failed of growth is left out of the final tooth form. These are the fundamental propositions presented in the explanation of the histological groupings of tissue and the short- ening of the tooth crown found in these cases. Figure 11 is a photomicrograph* of a little more than the incisal half of a crown of a central incisor, showing two zones of injury. Figure 12 shows an entire crown with a single zone of severe injury. In each of these the malnutrition was so severe as to arrest the growth of both enamel and dentin. In each an injury has occurred, affecting the incisal edge of the tooth. By comparing these with the diagram it is easily seen that when a certain thickness of growth of enamel had formed over this part, development was arrested and no more enamel was formed. In each case the enamel is thickest at the incisal edge and thins away to the groove which encircles the tooth crown, which is here presented in section. A band of very dark growth is seen under the new after-growth of enamel following the lines of Retzius on down to the dento-enamel junction. A comparison * Note. — In this work any photographic illustration made by reflected light will be called a photograph, even when moderately magnified. But when transmitted light through a thin section has been used, it will be called a photomicrograph. It has not been thought necessary to mention these terms in every instance. DYSTROPHIES OF THE TEETH. 15 now with the diagram shows that the growth has been arrested on the lines of accretion or lines of Retzius, as you may please to call these lines, Figure 10, in both cases. Also, it is seen that the second injury in Figure 11 is similar in plan to the first, differing in detail only because of the changed direction of the lines of accretion. In Figure 11 the incisal edge is broken, as usually occurs in these thin edges, but Figure 12 is from a tooth extracted soon after it came through the gums and all of the tis- sue formed is present. Figure 13 is an illustration with a much higher power of the labial side of the first zone of injury shown in Figures 11 and 12. Figure 14 is from the second zone of injury on the labial side. In these, the tissues and the lines of Eetzius are fairly well shown, and by studying the photomicrographs carefully, the relations of the tissues formed before and after the injury may be made out. It will be noted in Figure 13 that the one particu- larly dark band, which represents the surface of the enamel formed over the incisal edge, is continued under the enamel of second formation to the dento-enamel junction. Beginning a little farther from the incisal, a line of interglobular spaces appears in the dentin, and running almost parallel with the dento-enamel junction, continues on toward the incisal edge. Faint traces of these appear even in the small picture, Figure 11. With sufficient amplification, this line of interglobular spaces is found to continue to the incisal edge and join with the similar line from the opposite or lingual side ; that is, in the whole tooth it is a sheet or zone of interglobular spaces passing throughout the full extent of the dentin, of which this is a section. This line represents the injury in the dentin. It also represents more. It marks the boundaries of the old and the new formation of dentin and is the line on which these have been patched together. On the other hand, the one dark line in the enamel marks the line on which the new formation of enamel is patched onto the old. After a very careful study of sections from many of these teeth, it becomes clear that the part of the tooth which should have formed during the stoppage of growth was not formed at all. The enamel organ was destroyed through its whole thickness to the point where the dark line limiting the first enamel forma- tion reaches the dento-enamel junction, and when the second formation began it was telescoped over the old and laid down upon it, as shown in the illustration. The crown of the tooth was shortened that much, certainly, and may have been shortened very much more. When we study carefully Figure 12, with its single line of injury, and note how the little part of the incisal edge formed before the injury is literally sunken into that por- 16 PATHOLOGY OF THE HAED TISSUES OF THE TEETH. tion formed later, we must conclude that the shortening is much greater than that shown by the apparent telescoping of the parts. In the dentin the same thing occurs, only that it is expressed dif- ferently because of the different character of the tissue. The line of interglobular spaces shows where the second growth was telescoped into the first. A study of Figure 14 shows exactly the same plan in the arrangement of the tissue in the second zone of injury, including the overlapping of the new enamel onto the old and the accom- panying line of interglobular spaces in the dentin. The shorter overlapping of the enamel at the point of injury is due to the changed direction of the lines of growth. The actual shortening of the tooth may have been much greater. When we study the short and stumpy forms of many of the crowns of these mal- formed teeth, we must conclude that the shortening is often very much greater than this overlapping. It is this shortening and telescoping together of the different parts that is responsible for the greater part of the distortion of form so often observed in these teeth. It appears certain that the tendency is to form each of the parts on the lines that each would have had at the specified time of growth if there had been no interruption of the growth. We may gain another view of this by studying the lines of the labial dento-enamel junction. In the study of sections of many human incisor and cuspid teeth, this line is found to form a continuous curve from the incisal edge to the gingival line, as seen in the diagram, Figure 10. The amount of curve may vary indefinitely, but it is always a continuous curve in every normal tooth. In sections of these malformed teeth, this curve is found broken by a recurve at the zone of injury in every case, even in the lighter forms in which the growth seems not to have been completely arrested. This disturbance of the direction of this line seems to be due to the effort to form the second part on the lines that would have been laid down at that time if the growth had been going on regularly, and the larger and smaller are patched together. In the dentin the growth has been in abey- ance and the growth begins on the lines on which it was left off. But immediately the tendency is to enlarge to the greater out- line of the tooth as it would have been at the time had the growth not been interrupted. This causes a recurve in the line of the dento-enamel junction. In the enamel, the telescoping seems to be actual. That part of the enamel organ that had not arrived at the period of enamel building is uninjured and is pushed for- ward over the previously formed enamel and la5« down its layers of the second growth of enamel thus far over the old. No other Fig. 10. Fig 10 Diagrammatic illustration of the lines of Retzius, or incremental lines in the growth of the enamel, showing their direction in the different portions of the enamel cap. Fic. 11. Section of an incisor showing two zones of injury. Fig. 12. into the body of the crown of the tooth. End. Fig. 14. Fig. 13. Atrophy. A photomicrograph of a portion including the zone of injury nearest the incisal edge on the labial from the same section shown in Figure 11. In this the lines of Retzius may be seen in the enamel, also the dai'k line of junction between the enamel of first formation and enamel of second formation, reaching from the dento-enamel junction, with the enamel of second formation overlapping that of the first. The line of interglobular spaces in the dentin running almost parallel with the line of the dento-enamel junction, is well shown. Fig. 14. Atrophy. A portion including the second zone of injury seen in Figure 11. In this position the lines of Retzius diverge more sharply from the direction of the line of the dento-enamel junction, and the overlapping of the third growth of enamel onto the second is shorter. The discoloration fs greater. The line of interglobular spaces is broader, and in this position diverges more sharply from the line of the dento-enamel junction. Otherwise it is similar in plan with the first zone of injury shown in Figure 13. s>. — - \ , ^ ' ■J^-'^—y C. y A. Fig. 15. tion loward'Vcrow^'''^ section through portion of crown of =— "" r. Enamel. % ^J^^/t-on toward the roT '''='" ^'l^'hied tooth. ^. Direc- spaces, injury. Fig. 16. Fig. 17. ■'^'J'^V^^ Incisal end Fig. 18. Fig. 16. Labial surface of a central incisor, photographed to show the appearance of the groove. The dark color in parts of the groove makes it appear deeper than it really is. A part of a section cut from this tooth is shown in Figure 18. Fig. 17. Photograph of the lingual surface of the same tooth shown in Figure 16. Fig. 18. A photomicrograph of a portion of a section from labial portion of the central inci.sor. Figures 16, 17, showing a milder sort of injury, in which the growth of the enamel was interrupted but not permanently stoi)ped. The line of interglobular spaces literally divides the dentin of first formation from that of the second. The section was broken and the parts placed in position. A scrap of enamel was lost in preparation, as represented by the dotted line. Figs. 19, 20. Root of tooth parted on lines of growth. Photographed from the specimen extracted by the author. Photographs of a bicuspid tooth which had a zone of injury mid-length oif the root, and which was pulled apart in telescope form along the line of injury, i. e., the line of interglobular spaces. In Figure 19 the parts are photographed in normal position. In Figure 20 the two parts are separated, showing how they are telescoped together. Fig. 21. sort. jAn\F7£Z^^r;, -i't;;e*fretin.^roShi"'='f ^H^*^"--"^ ^^-^^^^ °f 'h as in F.gures 13. 14. but the discoloration L much W%^ *u^-^ '?*'"'^' ''^ ^^«" *" ^e away before e.xtraction in an effort to improre"fhe fppeara'nce '"""' "'^" ""^^ '^"' le severer - — the same edge had been ground DYSTROPHIES OF THE TEETH. 17 explanation of tlie phenomena is presented after the study of numerous cases. The discoloration that occurs in these teeth would seem to be an essential characteristic, if it were judged entirely by the teeth obtained for making sections. This material is very diffi- cult to find. Only extracted teeth can be used, of course, and few of them are extracted until so badly decayed that they are use- less, except those that are so badly discolored that patients and their friends urge their removal on that account. Examinations in the mouth reveal many cases of very considerable deformity without notable discoloration, as the photograph. Figure 8, taken from the mouth, attests. Many of the zones of injury show no discoloration. Numerous writers have given short descriptions of these teeth, scattering back for a hundred years. Most of these have dealt with the outward appearance only. Very few have pub- lished any studies of the histological characters, and most of these have been very brief and imperfect. Among the better should be mentioned Wedl, 1870; Baume, 1882; Walkoff, 1885. But by far the most important of the studies that have appeared is that by Dr. Otto Zsigmondy, of Vienna, Austria, in a paper pre- sented at the World's Columbian Dental Congress in Chicago in 1893. Unfortunately for Americans, no translation into English has been published. I personally examined many of Dr. Zsig- mondy's sections and learned further of his conclusions in con- versation. The one thing that impressed me then, and impresses me now, as I reread his paper, is his conviction that the tissue distortion has been produced by a condition that has been of very short duration, because the apparent zones of injury in the dentin were often — nearly always, indeed — so very narrow when con- sidered in their relation to the developmental lines. He could not, therefore, account for the marked deformity of these teeth. At the time he wrote he did not have the advantage of photo- micrographic reproductions, and his illustrations were very meager and insufficient. One of the best of them is reproduced in Figure 15. Figure 18 is a photomicrograph of a section of the labial portion of a zone of injury of the milder sort apparently, occur- ring in a central incisor. In this there was considerable discolor- ation of the enamel occurring irregularly along the line of injury in the labial surface, as shown in the photograph of the tooth, Figures 16 and 17. The discoloration in the line of the groove has the effect of a shadow in the photograph and makes the groove appear deeper in the discolored portions, which is not the fact. The particular section from which Figure 18 was made 18 PATHOLOGY OF THE HAED TISSUES OF THE TEETH. was chosen from a part showing the least discoloration. In this case the only distortion of the crown apparent in a superficial view of the tooth is the groove encircling the tooth and the dis- coloration. Also, the section shows that there was not a com- plete arrest of growth of the enamel. With a good light the enamel rods may be traced with the microscope through the darkest lines of the section, and they are seen to be well formed. There is no appearance of the telescoping process. The groove in the enamel appears much less pronounced in the section when highly magnified as shown, than it does in the photographs of the tooth. In the dentin, however, the injury is very severe, as shown by the clean-cut continuous line of interglobular spaces, which literally cut the dentin first formed from that formed later, and in the examination of the labial line of the dento-enamel junction in the full section, it is found to be distorted by a recurve, showing the interference with growth to have been pro- found and that some real shortening of the tooth must have occurred. As a further illustration of the possibilities in this class of injuries, I present two photographs, Figures 19 and 20, of a bicuspid tooth showing the separation of the telescoped parts in an injury of this kind occurring mid-length of the root. I extracted this tooth myself. The patient, a stranger, applied for relief from caries of bone of the upper jaw, and this tooth was situated on the border of the carious area in such position that it seemed to be best to remove it, though the tooth and its individual alveolar process were otherwise in good condition. At the moment of remo^dng the tooth, it was noticed that the apical portion of the root did not come away, but was pulled from its place and remained loose in the alveolus. Laying the tooth on the bracket with the forceps, this apical portion was picked out with the foil pliers and laid with the tooth for after examination, because it seemed to be a very curious break. The operation was completed and the patient dismissed with an appointment to return later for further treatment. On exam- ination, this tooth and root were found to have pulled apart like a telescope tube, and the telescoping was on the lines of growth of the dentin. Figure 19 shows the tooth and root placed together in the normal form, in which a marks the line of break. In Figure 20 the two parts are separated, showing how the apical portion telescopes into the body of the root. I suppose there was some severe illness of short duration at the time this part of the root was developing, which prevented the deposit of cal- cium salts, and a sharp, distinct and continuous line of inter- globular spaces occurred. At the time, the root was developed DYSTBOPHIES OF THE TEETH. 19 only as far as shown in the lower section of Figure 20, and had the broad conical opening shown at b. The internal diameter at the point to which the end of the apical portion reaches was of the size shown by the end of that piece. The result was that the solid dentin formed at that time represented only the lower square end of the upper piece. This was broken in the effort to extract and the root pulled apart on the line of the area of interglobular spaces, the line representing the lines of the proc- ess of growth. The patient failed to keep his appointment for further treat- ment and was not seen again. The opportunity to inquire into the nature of the nutritional disturbance that had caused this rare form of injury was lost. The specimen, however, tells its own story clearly. This case shows that the root of a tooth may also be injured by a condition of malnutrition, though such an extreme occurrence as this must be rare. I have noted a considerable number of cases in which a zone of injury occurred in the dentin beginning below the gingival line, as in the case shown in Figures 19, 20, though they are far more rare than those occurring in the crown of the tooth. Figure 21 represents another case of injury of the graver sort, occurring in a central incisor, in which but little discolor- ation is apparent. The wide overlapping of the new onto the older enamel, the complete breakage of the enamel rods along the line of junction of the two, the change in the course of the enamel rods in the two formations of enamel and the profound disturb- ance of and recurving of the labial dento-enamel junction, all point to a long suspension of nutrition and account for the grave distortion of the form of the tooth. This is much like that shown in Figure 12. The line of interglobular spaces is sharp and severe, but very narrow, and the dentin is normal immediately on either side. The incisal edge had been ground away in the endeavor to improve the appearance before the tooth, with the other incisors, was extracted. About one-third of the normal length of the crown had been missing. The next case is very curious in several respects. It is a bicuspid tooth that showed a very slight groove in the enamel not far from the gingival line. It was covered by the overlap- ping gum margin, except on the buccal surface. The whole tooth was, perhaps, as white as any normal tooth and was without any discoloration along the line of the groove, except that caused by a deposit of dark, closely adherent serumal calculus at several points. A photograph of this groove was but a partial success, as is shown in Figure 22. The tooth was then divided mesio- distally, preparatory to grinding sections. In examining the 20 PATHOLOGY OF THE HAED TISSUES OP THE TEETH. halves with a pocket lens, a curious zone of injury in the dentin was discovered, which was photographed at once as an opaque object, which is represented in Figure 23. Two sections, two thousandths of an inch thick, were prepared and mounted with- out removing them from the cover glass on which they were ground. The sections were beautiful. No one would suspect that there was any zone of injury in either dentin or enamel. The disturbance of the line of the dento-enamel junction and in the one section a clinging bit of serumal calculus were the only abnormalities discoverable by microscopic examination. The only way I could explain this was that the something that had been seen and photographed had become obscured by the balsam. The balsam was dissolved out and the section dried. A zone of fine interglobular spaces was then found with another singular appearance in the form of a broad line of demarkation, that could not be explained. The section was remounted in a very stiff balsam without using anything to clear the dentin, with the expectation of making a photomicrograph the same evening. Something prevented, and by the next evening, the day having been unusually warm, the interglobular spaces were again filled with balsam. The shadow, however, remained, and is presented in Figure 24. It has since been found that the condition pre- sented is common to a considerable number of the slighter injuries of this type. Figure 25 is a photomicrograph of a labio-lingual section cut from near the mesial side of a malformed tooth so that the line of interglobular spaces is cut through diagonally. This gives an exaggerated view of the zone of injury to the dentin, but will serve to impress the fact that these injuries are very severe. This presents this subject from its gravest to its slightest degree, in sufficient variety of cases to render the conditions intelligible. The Deformity in the Fiest Permanent Molars. The deformity of the first permanent molars should receive special consideration because of its greater frequence and because it so generally leads to early and rapid caries beginning in the malformed portion. The plan of injury does not differ from similar deformities in the front teeth, iDut the details of the injury are different because of the wide difference in the form of the tooth. Greater frequence of the occurrence of the condition in these teeth is due to the earlier beginning of calcification. In dissections of the jaws of the fetus at terra, I have usually found the calcification of this tooth just begun on the points of the cusps. Sometimes there are only small spiculae, in other cases Fig. 22. Fifi. 23. Fig. 22. Photograph of a bicuspid, showing imperfectly a slight groove from atrophy near the junction of the middle and gingival thirds of the crown. See Figures 23, 24. Fig. 23. The bicuspid shown in Figure 22 split mesio-distally and the cut surface photo- graphed as an opaque object. Note a broad zone of shadow in the dentin, extending in a semi- circular form from the groove on the mesial to the groove on the distal side. See also Figure 25. i Fig. 24. Fig. 24. A photomicroKraph from a portion of a section of the bicuspid shown in Figures 22, !!3, showing zone of shadow in the dentin as a result of interference with nutrition. Mark- ings of this character ai-e found in the mildest forms of interference with nutrition that show atrophy marks. Fig. 25. A photomicrograph from section of atrophied tooth cut diagonally to the zone of injury and serving to exaggerate the width of the zone of interglobular spaces in the dentin. This gives a stronger representation of the real injury to the dentin. Fig. 26. Fifi. 26. Photoeraph of cast showing atrophy of a first molar. Note that the occlusal por- tion of the tooth is much reduced in size. This is best appreciated by comparison with the second molar. Normally the occlusal surface of the first molar is the larger of the two. t. o 3 « ., S -> *-■ tfl rl — (- - '^ - "do" H t4 V4 c IS 01 T c , , c n y VH rt . a) c« o % M L. a tc c 4) -t-' n 1^, (l; X Tl H t- ^ c 0) o C3 X a c 3 a; m O -n C is F c E o u-o 3 c c o S gfl f: C3 a si <4H o « C8 SI « ? a 4) ^1 O X j= ^ ft ft 0) o ft o ft X be !S o 3 T3 CS 3 u p M t« o u X 01 C ■c JZ o O < o K 2 o a — ■6 u f H < w o 3 O 3 J 0=^-2 i^Z ft S ., _ o Ssoj; ofe S = ^^TS ^ V C.= C 01 ^■^5 3H-=5 cula the too ion .Is I- o X rtX ft CO ■"w'i •CSV o S ■w <0 i m f.-a xTs c c "Ji X ft s 01 -^ CX K C8x O CO ^ J espo! O O C IB KS o X .-5^" 1-?,- c C3 „ m ?: Q; < ^P ^5o -Si ,_ P.^-r '^r — 3«^ P'IG. 29. A iihotomicroffra))li from a portion of a mesio-distal section of a first molar show- insr in the section two zones of intevirlobular spaces. It shows only a part of the mesial half of the .section. Note that the line of interglobular spaces nearest the enamel, the first line, follows closely the dento-enamel junction. This follows the prominence of the mesial marjrinal ridne of dentin (on the left in the i)ieture) and then dips down to the jrinjrival. The line of injury to the enamel also rounds over this prominence and aicain touches the dentin just above the point of ending of the injury to the dentin. The second, and more marked zone of injury to the dentin, swings out quickly from the dento-enamel junction, on the left in the picture, and runs across much deeper in the tooth, showing the amount of dentin formed before this occurred. Fig. 30. An enamel whorl in the enamel near the dento-enamel junction, the surface of the enamel presenting a pit over the whorl. Normal enamel is marked A, A ; dentin, B, b ; the pit in the surface, c; the whorl, d. It will be observed that there is a hea\Y deposit of brownin in the deformed enamel, which lies next to the dentin. In fact, there is a recurve of the dento- enamel junction to partially accommodate the whorl. A little different direction in the cutting of the section, so that the pit in the surface would be missed, would show only the dark spot in the enamel and the whorl in the direction of the enamel rods, which would appear if the spot was not so black as to interfere with seeing the enamel rods. Fig. 31. Fig. 31. A photomicrograph of an enamel whorl beKinning in the midst of enamel tissues showing a failure of the development of enamel rod.-;. The pit is nearly filled with amorphous in the neighbox-hood is discolored. material, very dark in color, and much of the enamel Fig. 32. This photograph is from a skull found in the anatomical laboratory of the dental department of Creighton University by Dr. E. H. Bruening. All of the teeth of this individual presented the same deformity as those shown in the illustration. A section prepared from this skull was lost by accident. The scalloping was very regular. In this case the teeth presented an irregular wrinkling upon their surfaces, the wrinkles passing horizontally around the teeth. These wrinkled teeth have always a scalloping of the dento- enamel junction. Fig. 33. FIG 33 A cuspid a bicuspid and a molar tooth from Doctor Callow's case. These are fair represeniatfves of the appearance of the other teeth from the same mouth, from several of which sections were cut. An extreme case of wrinkled teeth. _:i^^ ^'♦^ Fig. 34. Fig. 34. Portion of enamel from near the gingival line on the buccal surface of a second molar from Doctor Callow's case. DYSTEOPHIES OF THE TEETH. 29 Department of Creighton University by Dr. E. H. Bruening. This defect has no relationship whatever to a definite period of mahiutrition, because it does not follow the lines of accre- tion, and is present in all of the teeth. In such cases the dento- enamel junction also shows much variation from the normal continuous curve, being wavy and in some cases very irregular. In the case illustrated in Figure 32 the dento-enamel junction was a series of quite uniform scallops. I show several illustrations of another case of this type of dystrophy, Figures 33, 34 and 35. I received from Dr. J. E. Callow, of Antigo, Wisconsin, sixteen teeth removed by him for a young woman who applied to him for treatment. They included incisors, cuspids, bicuspids and molars. The condition of these teeth, as indicated by their outward appearance, is very fairly shown in the photograph. Figure 33, of a cuspid, bicuspid and molar. All of the others were similar. Examination of these teeth showed that the injury to, or the deformity of, the enamel had no relation to contemporaneous lines of calcifica- tion. Histologically, although there were scattered interglobular spaces, there were no markings in the dentin that bore any rela- tion to those that occur in the accretional deformity. Either of these were sufficient to distinguish it as something different. In all of the teeth, from incisors to third molars, the deformity was greatest on the axial surfaces and least on the cutting edges and cusps. The surfaces were extremely rough and uneven, presenting sharp spiculas or knobs and deep pits in the utmost irregularity of form. Over some of the cusps the enamel seemed to be normally thick, but did not have the smooth glazed sur- face of normal enamel. Only occasionally a small area would show the normal smoothness. In most of the teeth the enamel assumed a normal appearance suddenly near the gingival line, and this normal part generally encircled the tooth, joining the cementum in a normal gingival line. Figures 34 and 35 are photomicrographs showing the pecu- liar histological characteristics of the enamel. In most of its parts the dento-enamel junction is lost in a wild jumble of cir- cular whorls or protrusions of enamel into the dentin. Quite a number of these whorls are hollow and empty, while some are filled with amorphous material, but all of these, without excep- tion, are lined with enamel, usually in the form of segments of whorls, as these are found in the bottom of other enamel pits. In some this lining is very thin. Some of these hollows commu- nicate with the surface by very small tubelike openings, while others seem to be closed on all sides. In occasional patches, even where the enamel began in these whorls along the dento-enamel 30 PATHOLOGY OF THE HARD TISSUES OP THE TEETH. junction, the rods to either side straightened up and closed over them into a fairly well formed enamel. Still, most of the formed enamel is a wild, twisting, curving and bundling of enamel rods. With all of this the enamel formed seemed to be of normal hard- ness in every part. In a considerable number of places the enamel is plunged deeply into the dentin in long prolongations that were too large and long to permit photographing with any lens with sufficient amplification to enable the structure to be distinguished. The illustrations show the characters of the departure from normal very much better than it can be por- trayed in words. In this case I could get no indication of any other abnormal condition of the patient. She seems to have been otherwise a normal and healthy girl. Many of the teeth were badly decayed and it is represented that all of them, whether decayed or not, were abnormally sensi- tive to sweets, heat and cold, and to acid fruits. Also, that this condition of sensitiveness had been persistent since the eruption of the teeth. This sensitiveness was so continuous and severe that it led finally to the removal of all of the teeth for relief. In all of my observation tliis unique case stands alone. I have, how- ever, observed in the mouth a number of cases that may have been of this character. The definiteness of the deformity and the perfectness with which this definite histological character was repeated in each tooth examined, indicates that it is a deformity to which the teeth are liable. This is emphasized by the frequent observation of the tendency seen along the line of the dento-enamel junction to form scallops and whorls in teeth otherwise normal. But I know nothing of the conditions leading to this kind of deformity. Dr. M. C. Smith, of Lynn, Massachusetts, presented casts of a case at Buffalo, at the meeting of the National Dental Asso- ciation, 1905, which seemed to me to be of the same character. "When I examined these models, no teeth had been extracted and no opportunity presented for a histological study. Dr. Smith's case presented the same difficulty as to sensitiveness. White Spots in the Enamel. White enamel is seen in occasional white or ashy gray spots occurring in the enamel of teeth otherwise normal in color and form. These white spots are usually small and are covered with the ordinary glazed surface of the enamel, so that an exploring tine will glide over them the same as over the perfect enamel. If, however, the spots are large, this glazed surface fails to cover the central portion, being projected but part way from the mar- gin toward the center. In that case, the central area is rough, Fig. 35. Fig. 35. Buccal cusp of a second bicuspid, from Doctor Callow's case. *6 Fig. 36. White spot in the enamel of an otherwise normal tooth. In the white area the enamel rods have no cementinK substance between them. They have a covering on the surface, however, that has the usual hard ttlaze common to the surface of normal enamel. This is Nay- smith's membrane. ■-^??*^»-. Fig. 37 Fin. 37. White spot in enamel. At the ri^ht, little bundles of rods are seen to be without cementing substance between them. 'J^ny*^ Fig. 38. Fig. 39. Flo. 38. Enamel from near the cusps of a tooth in Doctor Prunty's case, showing the enamel rods breaking into bundles which end in spiculie. This enamel had no cementing substance between the enamel rods. Its color was a dead paper-white. Fig. 39. A scrap from one of the best parts of enamel found in Doctor Prunty's case, showing the rods to be without cementing substance between them. DYSTROPHIES OF THE TEETH. 31 and an exploring tine enters the enamel without difficulty. Such spots as these latter are rare. Sometimes such a spot shows discoloration about its central portion or radiating through it in irregular lines or blotches. The smaller white spots covered with the glazed membrane are common in any great school clinic where large numbers of persons are present for dental oper- ations. A histological examination of these shows the enamel rods to be normal in their formation and continuous with the rods deeper in the enamel, which is altogether normal in form and color. Generally the smaller white spots that appear on the sur- face of the enamel do not extend through its thickness. It often ends abruptly in a line following the incremental lines of enamel formation, i. e., the lines of Ketzius, as seen in Figures 36, 37. In the area of the white spot there is no cementing substance between the enamel rods. This is the histological characteristic of all of these white spots that I have yet examined. This is, therefore, a dystrophy affecting the formation of the cementing substance between the enamel rods the same as certain of the pits in the enamel are a dystrophy of the enamel rods. White Enamel. I received fourteen teeth from Dr. D. J. McMillen, of Kansas City, which had been extracted by Dr. John Prunty, of Boyd, Texas, for one patient, all of which were deformed in what, from macroscopic examination, seemed a similar manner to that described in Dr. Callow's case. The teeth were very dirty with blood stains and from being handled, which obscured some of their most notable characters. But a closer examination showed the enamel to be soft. I found that it could easily be picked to pieces, and evidently much of it had been lost in this way since the teeth were extracted. The axial surfaces were made up of irregularly formed spiculae that rendered them extremely rough. Many of these had been broken, so much so, indeed, that it was with some difficulty that I was able to get sections showing the condition at the time the teeth were extracted. When I came to the making of sections of these, I found the enamel white through its entire thickness, not the white bluish color of enamel, but the white color of unglazed white paper. The enamel had seemed so frail that I had soaked the teeth in thin balsam and then thoroughly dried them, in order to retain the spicula? of enamel. This case proved to be something entirely different from Dr. Callow's case, histologically. The dento-enamel junction was perfectly normal in all its parts. Next to the dento-enamel 8a 32 PATHOLOGY OF THE HARD TISSUES OF THE TEETH. junction the enamel was in perfect form. But after a slight growth the enamel rods broke up into bundles that became smaller, and evidently these bundles had ended in spiculae. I found none of these that had not been broken, though I found patches with the mucoid film formed in the mouth still over them after grinding the sections, which showed conclusively that the spiculae had not been broken after the teeth were extracted. Figure 38 shows this and indicates very well the manner of the formation of these spiculas. Evidently the finest of these had been broken after the extraction of the teeth. In many places very little enamel remained. This enamel throughout all its parts was almost wholly without the cementing substance between the rods. Figure 39. Histologically, this was the principal deformity. I became satis- fied from my examination that the rods themselves were fully hard, but they were not cemented together and broke apart with the greatest ease. Indeed, much of the enamel came to pieces after it was mounted and the rods became scattered in the bal- sam. I have no idea what controlled the formation of the spiculae which constituted the principal outward deformity. In the mouth the teeth must have had a dead paper-white appearance. I have seen but one other case presenting a general absence of the cementing substance between the enamel rods. A laboring man came into the clinic at Northwestern University Dental School several years ago, whose teeth presented this dead paper- white appearance. Every tooth, and every part of every tooth, had this appearance. There was no deformity as to form. But Naysmith's membrane, which usually covers the enamel and forms the glaze of the surface, was absent. The teeth were of usual size, of good contour, and regular in the arch. He said they had always been so and he had been greatly annoyed because of the attention their peculiar color attracted. The man was twenty-eight years old. There were some points on the cusps where the enamel was worn enough to show the dentin, but gen- erally the wear was not excessive. He said he could chew food as well as anybody. There were three small proximal cavities in the bicuspids ; otherwise the teeth were sound. I partially excavated one of the cavities, found the dentin apparently of usual firmness, but the enamel seemed to crumble to pieces easily. Not only the walls of the cavity crumbled, but I could easily push a sharp explorer into the enamel of other teeth anywhere. I took some of the cuttings from the enamel walls of the cavity well beyond the decayed area and distributed them in glycerin under a cover-glass, and with the microscope found well-formed enamel rods that looked much like those that DYSTKOPHIES OF THE TEETH. 33 had been separated by a very weak acid, or those taken from the whitened enamel in backward decays. This condition of the enamel had not rendered the teeth more than ordinarily liable to caries, as was shown by the gen- eral soundness of the teeth. This condition reminded me strongly of the white spots so often seen in the enamel of teeth that are in the main per- fectly formed; and is undoubtedly of the same character. Fig- ures 36, 37. The only difference seemed to be that the usual white spots seen are covered with a very perfect glaze, or Nay- smith's membrane, so that a sharp instrument will glide over them. This man's teeth had no such glazed surface. A sharp explorer would catch anywhere with very little pressure. In fact, it would not glide over the surface at all. The teeth evi- dently had not a normal Naysmith's membrane. The enamel in the two cases seemed very similar to cutting instruments. One other, somewhat similar, case has come under my obser- vation in which the incisal portion of the incisors and cuspids and the occlusal portion of the bicuspids and molars were cov- ered with normal enamel, but a large part of the axial surfaces were white enamel, much of which lacked the glazed covering, or Naysmith's membrane. At all points this glazed membrane was projected to some distance from the normal over the abnor- mal enamel. These cases, taken together with the frequent occurrence of white spots, led me to the supposition that the failure of the cementing substance between the enamel rods is a special form of dystrophy or abnormality in formation to which the enamel is liable. The occurrence of this in isolated spots, which are usually of an ashy white color, is not very uncommon, but its occurrence in the whole of the enamel in the teeth of a person is certainly extremely rare. I have seen this in but the two cases mentioned, in the one with abnormal form, in the other with normal form. Nothing seems to be known of the pathology that brings about this condition. The study of such cases is of great importance, as it may lead to further knowledge of the formation of this tissue. Cer- tainly the facts developed show that either the functioning tissue or the functioning of the tissue that forms the enamel rods is so different from that which forms the cementing substance between the rods that the rods may be formed and the cementing substance fail. Also, we have seen in the illustrations many failures of the enamel rods with the space filled in part with something else apparently without histological form. This some- thing may be the cementing substance, 34 PATHOLOGY OF THE HARD TISSUES OF THE TEETH. MOTTLED TEETH.* In the years 1906 and 1907 several dentists resident in the Rocky Mountain region told me of a peculiar condition of the teeth in certain areas in their neighborhood, which they said was not found elsewhere, and which had not been described in the literature. This condition they called mottled enamel, or mot- tled teeth. I requested that some of the teeth be sent to me for examination, and after a time (1908) I received the crowns of a number of incisors with the astonishing report that the teeth of a very large proportion of the children in the areas mentioned were of the same character. All of the crowns I received were of incisors that had been cut away for the purpose of putting on artificial crowns to improve the appearance of the persons. Each of these was of normal tooth form. The lingual surfaces of these teeth were generally an opaque paper-white, but mottled with normal spots and clouded areas. The labial surfaces were in part of an abnor- mal white color, resembling white unglazed paper, but a consid- erable portion of the surface was mottled with dark brown. Some had black bands running across the labial surfaces ; some had dark brown bands bordered with yellow which faded away into a paper-white, with normal enamel toward the gingival portion; some of them had enamel of normal color over the immediate incisal edge, but this did not extend to the labial surface. All of the paper-white and discolored portions were opaque, having none of the translucency of normal enamel. In all of these teeth the usual glaze of the surface of the enamel was complete. That is, Naysmith's membrane, which covers the outer ends of the enamel rods, was normal. An exploring tine, the point of which was very hard and sharp, would glide over the surface without catching, the same as it would do over normal enamel. It was apparent that this was a type of dystrophy of the enamel of which nothing had appeared in dental literature. Not only this, but if the statements were correct, it was endemic in type. Heretofore no endemic conditions of the teeth have been known. Further, if the reports that from 70 to 100 per cent of the children reared in the various areas were afflicted with this condition, the cases were numbered by thousands, and the indi- vidual deformities were of a very grave character. • The description of mottled teeth is taken from an article written by G. V. Black, in collaboration with Dr. Frederick S. McKay, published in the Dental Cosmos, VoL LVIII, 1916, p. 129. Fig. 40. Fig. 41. Fig. 43. Fics -10 11 1' 43 Four illustrations of tlie mottled teeth. The area.s are irredular in out- line, and may be' dead white, or any shade of yellow or brown, or jet black. In certain re^tions where this condition is endemic, from 80 to 100 per cent of the persons who reside in the reK.on durins? the period of the formation of the enamel will have these mottled teeth. The labial sur- faces of the central incisors usually present the worst appearance. Fig. 44-A. Fig. 44-B. Fig. 44-C. Fig. 44-D. Figs. 44-a. b, c, d. These figures represent teeth that came to me split longitudinally and very perfectly in line. They had been cut off for the purpose of placing artificial crowns, and did not show the full length of the crowns. Figures A, B and c are central incisors, and Figure D is a lateral incisor. The surfaces were ground flat and polished : they were then set up with the cut surfaces toward the camera, the tooth being opened like a book, one-half laying on one side and one-half on the other. They were photograiihed in this position with about six diameters enlargement. The material did not make brilliant pictures, but it will be seen by scanning the labial mar.gins closely that the surface of the enamel is a different color from the inner portion. This may be seen also on the lingual surface, but it is not so prominent. This is the injured part of the tooth in mottled enamel. The thickness of the injury can be made out by careful examination of the figures. Fig. 45. Fig. 45. Photomicrograph of a section of moderately darlc enamel from a mottled tooth. There is no cementing substance between the enamel rods, the space being filled with brownin. Fig. 46. Fig. 46. Showing the distribution of the brownin between the enamel rods, as at A, B, C,_ D. In Figure 47 the color in the section is just as it was in the tooth before it was cut, not having been changed in the least. DYSTROPHIES OF THE TEETH. 35 I went into the examination thoroughly aroused to its importance, and in 1909 visited a number of susceptible areas and studied the conditions on the ground. The essential malformation in this condition is the failure of the cementing substance between the enamel rods in the outer one-fourth to one-third, more or less, of the surface of the enamel. When this exists alone the enamel is a dead paper- white. In many of the cases a coloring matter is found in place of the cementing substance between the enamel rods, and on this hinges the great variety of appearances. Some of the teeth are a paper-white that glares and impresses itself as something abnormal whenever the person opens his lips, some are brown, some nearly black, some quite black. Every degree conceivable of the co-mingling of color — natural white, paper- white, yellow, brown and black, is found.* (See Figures 40, 41, 42, 43.) BEOWNIN. Since I commenced the study of the mottled teeth I have, as occasion has offered, been studying the coloring matter, which is one of the very ugly features of this condition. In this study I have found this same coloring matter, so far as I am able to determine, in most kinds of malformation of the enamel. Espe- cially is it abundant in the contemporaneous accretional defor- mities. It is a dark brown coloring matter that is deposited in much more than half the cases in which the enamel rods are not cemented together with the normal cementing substance. In the enamel whorl we find this coloring deep in the enamel, some- times actually lying against the dento-enamel junction, making a very dark spot in a section, while the surface of the tooth is fair. The coloring matter is the same material, and its reaction to dissolving agents is the same in all of these various condi- tions. I have dissolved it out and made such teeth very white. In an effort to find a suitable name for this coloring matter for use in dentistry I have used the word brownin, which seems to me in good form as a nomenclature word. * Note. — Different views have been expressed by those who have studied these teeth as to the time at which the discoloration occurs, whether before or after the ruption of the teeth. Dr. G. V. Black, from histological studies of a few teeth, thought the discoloration was caused by the deposit within the open spaces between the rods of a brownish stain before the teeth erupted. (See Dental Cosmos, Vol. L/VIII, 1916, p. 142. ) Dr. F, S. McKay, after very extensive observation of hun- dreds of cases over a period of ten years or more, states that the teeth are white when they erupt and the discoloration occurs very gradually afterwards. (See Dental Cosmos, Vol. LVIII, 1916, p. 628.) 36 PATHOLOGY OF THE HAED TISSUES OF THE TEETH. HISTOLOGICAX. CHAEACTEEISTICS. The mottled teeth which I received were split labio-lingually through their centers longitudinally when they came to me. Many of the crowns were incomplete in that they had been cut from the roots some little distance from the gingival line. I ground the broken surfaces flat, polished them, and photo- graphed them mounted in the pairs from each tooth. These were photographed by reflected light with enlargements of from six to eight diameters. (See Figures 44a, 44b, 44c, 44d.) The material did not give very brilliant pictures, but they showed the outlines of the imperfectly developed enamel. Sections were then ground for microscopic study. They presented a very considerable variety of injuries. The teeth were all from young persons, and were practically unworn except a few on the incisal edge. The enamel was normal in its outline form and normal in thickness in all of the specimens, but not normal in color. The group presented, as I found later by personal examination of many children, a series of bad cases of mottling. Some portions of the enamel were perfectly nor- mal, both in color and histological development, in the majority of the specimens. A number of them were of a very dark brown color over a considerable portion of the labial surfaces, shad- ing from the brown areas through varying shades of yellow, to opaque paper-white, and from this into the normal enamel color. All of the abnormal areas showed the same lack of devel- opment of the cementing substance which usually binds the enamel rods together. The degree of this injury varied in the different teeth and in the different parts of the crowns of indi- \adual teeth. Later, in examining the children, I saw many teeth that were much darker in color than those I had for cutting. This, however, was only a matter of degree of injury without difference in kind. In all of the specimens the enamel rods were well formed throughout; in the imperfect areas the enamel rods seemed as regular and perfect in form as in the areas in which the cement- ing substance between them was normal. In areas in which the difficulty was simply a lack of the cementing substance which should be between the enamel rods, the spaces were empty, or filled with air. Such areas were opaque paper-white because of the presence of air between the enamel rods. In the dark-colored areas the brownin was found to be in the spaces between the enamel rods. The enamel rods them- selves were as perfect and presented the same cross markings as in normal teeth, but they often made very dark photomicro- DYSTROPHIES OP THE TEETH. 37 graphs. (See Fig. 45.) The lines of accretion in the growth of the enamel were about as usual in normal enamel. It was particularly notable that the lines and depths of the abnormal condition had no reference whatever to the lines of accretion or growth in the formation of the enamel, thus showing a remarkable difference from the contemporaneous accretional deformities of the enamel, in which the lines of accretion in the growth of the tooth are very closely followed. In the illustration. Figure 46, it will be noticed that there are areas or lines of brownin distributed deeply in the enamel. The yellow shades of stain seem to be caused by brownin within the substance of the enamel which is covered by normal enamel. In this case the modification of color is caused by the partial showing of the brown through the translucent covering. In other cases the yellow color appears to be caused by minute areas of brownin too small for the nailed eye to distinguish as separate, and the mingling of this with the translucent white gives the yellow shades. In my sections I found no yellow col- ors whatever. Distribution of brownin in the enamel as a whole is extremely irregular. In the darkest areas I found in the teeth furnished me, it was difficult to make a photomicrograph that would show all of the spaces between the rods filled. Many of them are empty. This character of the deposit is quite well shown in Figures 46 and 47, which were made with low enough power to show the whole of the incisal portion of the teeth. The sections cut from teeth that have been mounted for grinding in very light-colored shellac show plainly that the limit of the imperfect enamel is not a sharp line, but that some of the spaces are open between the enamel rods much deeper than others. This causes the color produced by brownin to thin out into the perfect enamel. There are also in this enamel many places where the color seems to be about normal, in which small groups of spaces between the enamel rods are filled with the brownin. This is very sharply brought out in some of the photomicrographs. Many of these islands of color are so small as to escape obser- vation with the naked eye, but come out prominently with the medium powers of the microscope. MOTTLED ENAMEL A NEW PEOBLEM IN DENTAL PATHOLOGY. Endemic white enamel, or mottled enamel, presents an entirely new problem in dental pathology. Nothing of the kind seems to have been discovered heretofore in any part of the 38 PATHOLOGY OF THE HARD TISSUES OF THE TEETH. world. This endemic feature gives this description unusual nov- elty. When I visited a number of susceptible areas during the summer of 1909 I examined the children, and many of adult age, myself. Great numbers of children seemed to be easily gathered. It was quickly seen that the reports had not been exaggerated. The settlement of these regions is comparatively recent, and about half of the children were born and passed the earlier part of their lives elsewhere. I spent considerable time walking on the streets, noticing the children in their play, attracting their attention and talking with them about their games, etc., for the purpose of studying the general effect of the deformity. I found it prominent in every group of children. One does not have to search for it, for it is continually forcing itself on the attention of the stranger by its persistent prominence. This is much more than a defor- mity of childhood. If it were only that, it would be of less conse- quence, but it is a deformity for life. The only escape from the deformity is by the placing of crowns, and possibly of bridges or artificial dentures later in life. SPORADIC CASES. A few sporadic cases have been seen from different sec- tions of the country which, in considerable part, simulate the endemic cases. I have a photograph showing the upper incisors of a person born and reared in Chicago which are much like the endemic condition. There are also some white flecks on sev- eral of the other teeth, but these are slight. Another case is that of a boy who grew up on a farm in Indiana. The incisors were badly marked with a dark band across their labial surfaces. All of the other teeth were normal. I have seen two other spo- radic cases of this character, but failed to obtain photographic records of them. DIAGNOSIS. The diagnosis of mottled enamel is usually not difficult, as the areas are generally most prominent on the labial surfaces of the incisors, particularly the central incisors. (See Figures 40, 41, 42 and 43.) In studying these cases as representing an endemic condition, it becomes important to associate the age of the individual with the mottled areas on the various teeth. Faults in the form or color of the teeth may occur from errors in growth, or may occur from causes acting upon them after the teeth have been fully formed. Any departure from the normal in the enamel of the teeth, the dentin, or the form of the teeth, from errors in development, must occur while the e Flo. 47. In examinitiK this figure the reader should have fixed in his mind the followinfr: The substance of the jjeifectly developed enamel of the tooth has not been successfully staint'il ; being a solid, it will absorb nothing into itself, therefore any staining in the substance of the enamel is the result of imperfect development which creates openings which will receive a stain. The photomicrograph is of a portion of the crown of an incisor tooth from which all traces of color had been dissolved out, making the tooth very white. The piece was placed in aJcohol for several days and then transferred to a solution of shellac which had been tinted with gentian violet. After remaining in that for two weeks it was mounted upon a cover-glass and dried for grinding, and a section was cut. In studying this it will be seen that the labial surface of the tooth — the portion most injured by failure of the cementing substance between the enamel rods — has come out black. On the lingual surface a very different phenomenon occurs. Here the injury has been much milder than on the labial surface, and it will be seen that areas of white run through the dark areas, and that the brownin shows in long lines instead of making a full brown. This shows that only a portion of the cementing substance between the enamel rods has failed. *6 TABLE I. T.vm'LAR Statement of the Eesults of an Examination for Mottled ano Noumai. Teeth Among the School Children in L and Vicinity. {Prepared by G. V. Black, July 12, 1909.) -a ji Born elsewhere in Born in other | s Rocky Mtn. region states. H S " 1 1 11 11 '- 03 11 < i It i i 1 !:3 6 o ^ "o 1 o la g o c3 'o IS 1 £2 3,254 131 120 2,945 811 116 87.5 231 162 57.2 410 1,215 25.2 135 0 17 118 29 3 90.6 17 8 68 0 9 52 14 7 17S 1 - 1 176 71 4 94 6 14 9 39.1 14 64 17.9 3,567 132 144 3,239 911 123 88.1 262 179 59 4 433 1,331 24.5 2,945 118 176 3,239 Of eases with teeth mottled, 40 per cent, or 642 children, have brown stains also. The deciduous teeth examined (132 children) were found normal. Note. — First, there is a statement of the number of children in the schools in which examinations have been made. Second, those examined are divided into three classes: Native-born; born elsewhere in the Eoeky Mountain region; born in another state. In case of the latter two classes, the age at which they became residents here is given in Table II. TABLE II. Detailed Statement of Results of Examination for Mottled and Normal Teeth Among the School Children Who Became Residents After Birth Elsewhere. (Prepared by G. V. Black, July 13, 1909.) Bicuspids and second molars. Incisors, cuspids, and first molars. Third molars. Out of not danger, noted "L" Age when be- came resident. |- Years . . /Mottled \Normal /Mottled [Norma! 1 35 8 102 25 II 1 0 2 0 3 4 2 17 0 76 34 1 1 (1 n 1 0 1 1 3 15 3 41 39 2 II 3 1 3 2 2 1 4 22 5 56 57 0 1 2 II 1 0 1 1 5 12 4 39 80 5 1 4 1 1 2 4 6 14 28 87 0 1 1 1 2 1 6 7 8 4 20 123 ; 0 5 0 0 1 8 8 8 10 9 120 2 0 0 4 0 1 0 6 9 4 5 9 129 1 0 3 0 0 0 4 10 s 5 4 105 (1 I 4 0 0 0 4 11 5 4 8 88 1 0 s 1 1 2 5 12 2 5 4 87 0 II 1 1 0 3 13 fi 2 13 56 3 14 1 0 1 49 4 15 0 1 0 211 16 17 18 19 0 another state. 15 1 II 5 15 "Y" Born tisp- where in stale. Born in another state. /Mottled [Normal /Mottlc